Estrogen and progesterone promote breast cancer cell proliferation by inducing cyclin G1 expression

Breast cancer is the most common cause of cancer among women in most countries (WHO). Ovarian hormone disorder is thought to be associated with breast tumorigenesis. The present study investigated the effects of estrogen and progesterone administration on cell proliferation and underlying mechanisms in breast cancer MCF-7 cells. It was found that a single administration of estradiol (E2) or progesterone increased MCF-7 cell viability in a dose-dependent manner and promoted cell cycle progression by increasing the percentage of cells in the G2/M phase. A combination of E2 and progesterone led to a stronger effect than single treatment. Moreover, cyclin G1 was up-regulated by E2 and/or progesterone in MCF-7 cells. After knockdown of cyclin G1 in MCF-7 cells using a specific shRNA, estradiol- and progesterone-mediated cell viability and clonogenic ability were significantly limited. Additionally, estradiol- and progesterone-promoted cell accumulation in the G2/M phase was reversed after knockdown of cyclin G1. These data indicated that estrogen and progesterone promoted breast cancer cell proliferation by inducing the expression of cyclin G1. Our data indicated that novel therapeutics against cyclin G1 are promising for the treatment of estrogen- and progesterone-mediated breast cancer progression.

Expression of P27(kip1) and cyclin G in patients with acute leukemia and its correlation / 中国实验血液学杂志

This study was purposed to explore the expression of P27(kip1)and cyclin G in patients with acute leukemia (AL) and its correlation. The reverse polymerase chain reaction (RT-PCR) was used to analyse the expression of P27(kip1) and cyclin G mRNA in 89 AL patients and 10 normal persons; Western blot was used to analyze the expression of P27(kip1) and cyclin G protein in 39 AL patients and 10 normal persons. The results showed that the cyclin G mRNA and protein expressions in new diagnosed/relapsed cases of AL were significantly higher than those in patients with remission and normal controls (p < 0.05 and p < 0.01), but there was no difference between remission cases and normal controls (p > 0.05). The expression of P27(kip1) mRNA in newly diagnosed/relapsed patients with AL was not significantly different from patients with remission and normal controls (p > 0.05), while the P27(kip1) protein expression in remission cases of AL and normal controls was significantly higher than that in new diagnosed/relapsed cases (p < 0.05), but there was no difference between remission cases and normal controls (p > 0.05). The expression of P27(kip1) negatively and lowly correlated with the expression of cyclin G in patients with AL. It is concluded that the low expression of P27(kip1) and the high expression of cyclin G in patients with AL may have some correlation with genesis and development of AL and may be an indication for poor prognosis of AL.

The progesterone-induced expression of cyclin G1 and its effect on the proliferation of mouse uterine epithelial cells / 生理学报

The aim of the present study is to investigate the effect of progesterone-induced expression of cyclin G1 on the proliferation of endometrial epithelial cells. To obtain mouse endometrial epithelial cells, the uteri were isolated from ovariectomized mice which were injected subcutaneously with 100 ng estradiol per day for two days. Then the uteri were digested by dispase and pancreatin respectively. Endometrial epithelial cells were cultured in DMEM/F12 containing 6% fetal bovine serum, and divided into four groups when they grew to confluence. Each of the groups was treated as follows: Group E was treated with 0.01 micromol/L estradiol only, group P was treated with 1 micromol/L progesterone, group EP was treated with both 0.01 micromol/L estradiol and 1 micromol/L progesterone, and group C was treated with 0.01% DMSO for control. Immunocytochemistry was used to examine the expression of cyclin G1 protein. MTT assay was used to evaluate metabolic activity of cells. Flow cytometry was used to check the number of cells distributing in each phase of the cell cycle. The result of immunocytochemistry showed that there was no expression of cyclin G1 protein in group C and group E, while cyclin G1 was obviously expressed in group P and group EP and localized in nucleus. In the MTT assay, compared with group C, the viability of group E significantly increased, while that of both group P and group EP decreased significantly. The results of flow cytometry were in accordance with those of MTT, which showed that compared with group C, group E had a higher proportion of cells in S phase, while group P, as well as group EP had a lower proportion of cells in S phase but a higher proportion in G1 phase and G2/M phase. These results indicate that progesterone could induce cyclin G1 expression in the primary culture of mouse endometrial epithelial cells, meanwhile inhibit the proliferation of cells and block the cell cycle progression. Thus, progesterone-induced expression of cyclin G1 is probably a negative factor in regulating cell cycle, which is involved in the inhibitory effect of progesterone on the proliferation of endometrial epithelial cells.

Expression of cyclin G1 in laryngeal squamous cell carcinoma and its clinicopathologic significance / 中华病理学杂志

<p><b>OBJECTIVE</b>To evaluate the expression of cyclin G1 and its relationship with clinical pathological characters, p53 expression and microvessel density (MVD) in laryngeal squamous cell carcinoma (LSCC), and to investigate the prognostic value of cyclin G1 in LSCC.</p><p><b>METHODS</b>Using immunohistochemistry, 81 cases of LSCC were evaluated for cyclin G1 and p52 expression, MVD was assessed by CD34 staining. In 20 cases, similar assessment was made in the adjacent normal mucosa.</p><p><b>RESULTS</b>Compared to the normal laryngeal mucosa, the expressions of cyclin Gl, p53 and MVD were higher in LSCC than that in normal tissues. The positive rates of cyclin G1 and p53 expressions in LSCC were 61.7% (50/81) and 65.4% (53/81), respectively. The positive rates of cyclin G1 in LSCC with or without p53 expression were 71.7% (38/53) and 42.9% (12/28), respectively. The expression of cyclin G1 was significantly correlated with p53 (P = 0.011). The mean value of MVD was (51.23 +/- 16.46 mv) in cyclin G1 positive group, and(30.74 +/- 12.29 mv) in the negative group, and the difference was significant (P = 0.005). Furthermore, the over-expression of cyclin G1 was related to the histological grade, cervical lymph node metastases and 5 year survival (P = 0.002, 0.013 and 0.032 respectively).</p><p><b>CONCLUSIONS</b>Cyclin G1 is highly expressed in laryngeal squamous cell carcinoma, and is associated with the expression of p53 protein and tumor angiogenesis. It may play an important role in carcinogenesis and metastasis in LSCC, and may be one of prognostic indices for LSCC patients.</p>

Relationship between cyclin G1 and human papilloma virus infection in cervical intraepithelial neoplasia and cervical carcinoma / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate the overexpression of cyclin G1 in cervical intraepithelial neoplasia (CIN) and cervical carcinoma, and the correlation between cyclin G1 and high-risk human papilloma virus (HPV) infection.</p><p><b>METHODS</b>All of the specimens were obtained from the Department of Pathology of China-Japan Friendship Hospital from January 2000 to August 2004. We detected the expression of cyclin G1 with immunohistochemistry, HPV16/18 infection with in situ hybridization, and high-risk HPV infection with Hybrid capture system II (HC-II) in normal group (25 cases), CIN I (48 cases), CIN II (56 cases), CIN III (54 cases), and invasive cervical squamous-cell carcinoma (SCC, 31 cases).</p><p><b>RESULTS</b>The positive rates of cyclin G1 expression in CIN (77.85%) and SCC cervical tissues (87.10%) were significantly higher than normal (8.00%, P < 0.01), and the intensities of cyclin G1 expression in CIN (40.60%) and SCC cervical tissues (61.51%) were significantly higher than normal (2.72%, P < 0.05). The positive rates and intensities of cyclin G1 expression increased gradually with the grade of cervical lesions. High-risk HPV infection rates were higher in CIN and SCC than normal groups (P < 0.05). There was a positive correlation between cyclin G1 expression and high-risk HPV infection detected with HC-II (Kendall's tau-b = 0.316, 0.269, 0.352, and 0.474 in CIN I, CINII, CIN III, and SCC, respectively, P < 0.05).</p><p><b>CONCLUSIONS</b>Cyclin G1 is overexpressed in CIN and SCC. Cyclin G1 may be a biomarker for detecting CIN and SCC. Cyclin G1 may play an important role in the oncogenesis of CIN and SCC by high-risk HPV infection.</p>

Proliferation regulation effect of cyclin G1 antisense oligodeoxy-nucleotides with liposomal transfection on HL-60 cell / 中国实验血液学杂志

To investigate the effect of cyclin G1 antisense oligodeoxynucleotide (ASON) with liposomal transfection on mediating proliferation of HL-60 cell, the cyclin G1 ASON with liposomal transfection was used in vitro in co-culture with HL-60 cell, the protein and mRNA expression levels of cyclin G1 were measured by immunocytochemistry assay and RT-PCR. The cell apoptosis was detected by electron microscopy, in situ cell apoptosis detection kit (POD), DNA gel electrophoresis and flow cytometry (FCM). The results showed that in the cyclin G1 ASON group the protein and mRNA expression of cyclin G1 were significantly inhibited as compared with sense oligodeoxynucleotide (SON) group and blank group. When the ASON concentration increased, the proliferation ratio of HL-60 cell and CFU of HL-60 were also significantly inhibited. There was apoptosis of HL-60 cell. In conclusion, cyclin G1 ASON can specifically inhibit its protein and mRNA expression levels as well as the HL-60 cell proliferations and can accelerate the apoptosis of leukemia cells with concentration-dependent effect of ASON.

Effect of cyclin G1 antisense oligodeoxynucleotides (ASON) on the growth of HL-60 cells in nude mice / 中华血液学杂志

<p><b>OBJECTIVE</b>To study the inhibition effect of cyclin G(1) antisense oligodeoxynucleotides (ASON) on the growth of HL-60 cells in nude mice.</p><p><b>METHODS</b>(1) Nude mice were divided into control group, sense oligodeoxynucleotides (SON) group and ASON group. After (60)Co radiation, with HL-60 cells SON group and ASON group were subcutaneously innoculated; (2) The weight and volume of tumors were continually measured; (3) The morphology of tumor cells was observed by microscope; (4) The protein and mRNA expression levels of cyclin G(1) were determined by flow cytometry (FCM) and reverse transcription polymerase chain reaction (RT-PCR); (5) The cell apoptosis was detected by electron microscopy and FCM.</p><p><b>RESULTS</b>(1) The inhibition rate of tumor in ASON group was 69.4%. In ASON group, the wight and volume of tumor were significantly lower than those in SON group and control group. (2) The HL-60 cells in ASON group showed morphologically smaller nuclei, less mitosis, less heteromorphosis and apoptosis.</p><p><b>CONCLUSION</b>The cyclin G(1) ASON can inhibit the growth of HL-60 cells in nude mice and induce apoptosis.</p>